Al对过共析钢缓冷相变和过冷奥氏体动态相变组织的影响

EFFECTS OF ALUMINUM ON THE MICROSTRUCTURES OF TRANSFORMATION DURING SLOW COOLING AND DYNAMIC PHASE TRANSFORMATION OF UNDERCOOLED AUSTENITE OF HYPEREUTECTOID STEEL

利用Gleeble 1500热模拟试验机进行单轴热压缩实验,研究了合金元素Al对过共析钢缓冷相变和过冷奥氏体动态相变组织的影响.结果表明:在缓冷相变时,Al的加入抑制网状渗碳体形成,细化珠光体片层间距;在过冷奥氏体形变过程中,动态转变经历动态相变和相变所得珠光体中渗碳体球化及铁素体动态再结晶等过程.在动态相变过程中,没有形成晶界网状渗碳体,而直接产生珠光体.Al的加入使动态相变过程中奥氏体的稳定性提高、珠光体转变推迟,进一步细化了珠光体片层间距.在相变所得珠光体中渗碳体球化及铁素体动态再结晶的过程中,Al阻碍渗碳体粗化,使渗碳体颗粒和铁素体晶粒尺寸细化.

The effects of Al on the microstructures of transformation during slow cooling and dynamic phase transformation of undercooled austenite of hypereutectoid steel were investigated by hot uniaxial compression tests. The results indicate that during transformation of slow cooling, the proeutectoid cementites are restrained and interlamellar spacing of pearlite is decreased with the addition of Al. During deformation of undercooled austenite, the dynamic transformation includes dynamic phase transformation, spheroidization of cementite and dynamic recrystallization of ferrite. During dynamic phase transformation, the proeutectoid cementites are hampered and the pearlite is obtained. With the addition of Al, the stability of undercooled austenite during deformation is increased, the formation of pearlite is retarded and the interlamellar spacing of pearlite is reduced. During the spheroidization of cementite and dynamic recrystallization of ferrite, the coarsening of cementite is hindered, and the sizes of cementite particles and ferrite grains are refined by the addition of Al.